Math::Expr::VarSet - Represents a set of variables and there values
Used to represent variables with values and substitutions.
Create a new VarSet object.
Sets $var to $val. Returns 1 if the $var was already set to $val ore did
not have a value previously, otherwise 0.
Inserts all variables from $set into this object
Returns a stringrepresentation of the set, usefull for debugging.
Returns the value of $var.